Continuous plating system

ABSTRACT

A system for the continuous plating, cleaning or rinsing of articles wherein all surfaces of the articles are uniformly and entirely exposed to the fluid through which they are conveyed. A trough suspended within a fluid bath is operative to cyclically move forward and upward and abruptly return to its initial position thereby to cause articles in the trough to inertially fall to positions successively forward of the trough and in new positions with respect to the trough and other articles.

United States atent [72] Inventor Elbert R. Faust Woodbury,Conn. {21] AppLNo. 796,033 [22] Filed Feb.3, 1969 [45] Patented Oct.26, 1971 7 m1 gn M eTwQhs l iwliln New York, N.Y.

[54] CONTINUOUS PLATING SYSTEM 7 Claims, 3 Drawing Figs.

[52] user 204/193,

134/160, 204/201 [51] Int.Cl ..B65g49/02 [50] FieldofSearch 204/198, 222, 199, 201; 118/70; 134/160, 164; 198/218 [56] References Cited I UNITED STATES PATENTS 815,027 3/1906 Meaker 204/198 913,747 3/1909 Meaker 204/198 2,164,710 7/1939 Hatch 204/198 FOREIGN PATENTS 1,573 11/191 1 Great Britain 204/222 366,401 2/1932 Great Britain 204/222 Primary Examiner-John H. Mack Assistant Examiner-W. 1. Solomon Attorney-Weingarten, Maxham & Schurgin ABSTRACT: A system for the continuous plating, cleaning or rinsing of articles wherein all surfaces of the articles are uniformly and entirely exposed to the fluid through which they are conveyed. A trough suspended within a fluid bath is operative to cyclically move forward and upward and abruptly return to its initial position thereby to cause articles in the trough to inertially fall to positions successively forward of the trough and in new positions with respect to the trough and other articles.

PATENTEUUCT 26 I971 /ld uu uv a INVENTOR.

ELBERT R. FAUST ATTORNE S CONTINUOUS PLATING SYSTEM FIELD OF THE INVENTION BACKGROUND OF THE INVENTION Articles to be electroplated are conventionally processed on a batch basis. In one well-known electroplating system, items to be plated are loaded into a basket which is transported by means of an elaborate manually or automatically controlled conveyor mechanism through the necessary cleaning, plating and rinsing baths. In another known plating system, items are loaded into a rotatable barrel which is then lowered into a plating solution and rotated therein to plate the items contained within the barrel. These plating systems are rather complex and, since they operate on a batch-by-batch basis, are limited in the speed with which plating can be effected. The inherent slowness of these conventional systems, together with the additional labor required in loading and unloading items being processed, increases the cost of plating and correspondingly adds to the cost of articles so plated. Moreover, it is often difficult by such conventional techniques and systems to provide a complete and uniform coating on articles, especially on relatively small articles such as electronic components. In addition, conventional systems can often damage or tangle items being processed since the items are usually tumbled or agitated to provide uniform coating.

SUMMARY OF THE INVENTION In accordance with the present invention, a continuous electroplating system is provided wherein small articles are effrciently, uniformly and entirely plated by apparatus which is relatively simple and yet especially adapted for high-volume continuous production plating. The system comprises a novel and particularly effective conveyor assembly operative to transport items to be plated in an essentially continuous manner through a plating bath and in a manner which achieves uniform coating with substantially no damage to the items. A trough is suspended or mounted within a plating bath and is operative to cyclically move forward and upward in a smooth manner and abruptly return to an initial or rest position such that items resting within the trough are carried forward and upward during the smooth movement of the trough without changing position, and as the trough abruptly returns to its rest position, the items are caused to inertially fall to new positions forwardly of the trough. The items progress through the plating solution in this periodic manner randomly falling to new positions during each return motion of the trough. In practice, items to be plated are loaded into the supply end of the trough by suitable conveyor means, the items advancing through the plating bath by the periodic inertial motion just described. Plated items leave the trough at the discharge end of the bath by similar periodic motion and are deposited onto suitable conveyor means for transport out of the plating solution and into subsequent cleaning or rinsing baths, as required in a particular process.

The trough is generally fabricated of an electrically insulative material compatible with the plating solution employed and has an electrode structure provided in the floor thereof which is constructed to suit particular process requirements. The novel system operation permits relatively simple replenishment of plating fluid, and permits efficient arrangement of electrodes within the plating bath. The invention can also be employed in cleaning and rinsing baths of an electroplating system to uniformly process the items, and is useful generally for the processing of items where uniform and complete exposure to an immersing fluid, which can be liquid or gas, is desired.

DESCRIPTION OF THE DRAWINGS The invention will be more fully understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a diagrammatic elevation view of a plating system according to the invention;

FIG. 2 is a sectional end view of the plating system of FIG. 1; and

FIG. 3 is a sectional cutaway view of an alternative embodiment of the trough of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION A plating system especially useful for the continuous plating of small articles is illustrated in FIG. 1 and comprises a plating tank 10 containing a suitable plating solution, a trough conveyor l2 pivotally mounted within the plating bath, supply means 14 for directing items to be plated into the trough, and conveyor means 16 operative to remove plated items from the bath. Trough conveyor 12 includes an elongated trough of channel-shaped cross section formed of an electrically insulative material, typically plastic, which is compatible with the fluid in which it is immersed. The trough 18 is disposed below the surface of the plating solution and arranged for motion within the plating tank along the longitudinal axis thereof. Trough 18 is pivotally supported by hangers 20 and 22 disposed near respective opposite ends thereof, the hangers being pivotally attached at their lower ends to trough l8 and pivotally attached at their upper ends to a rigid support 24. The trough is thus supported by a parallel suspension system which allows pivotal parallel motion thereof; in other words, longitudinally and upwardly motion parallel to the plating bath surface.

A supply pipe 26 is disposed within the plating bath with its orifice or orifices oriented centrally of trough 18 to provide a controlled flow through or into the trough to suit particular process requirements. A conductive rod or plate 28 disposed in the bottom surface of trough 18 serves as the cathode electrode while an elongated perforated member 30, or basket, disposed within or above trough 18 serves as the anode electrode. Other well known electrode configurations, such as anode hangers or danglers can also be employed. Electrical connection is made from cathode 28 to cathode bus bar 32 by means of a cable 34 which extends from bus bar 32 through hanger 20 to cathode plate 28. Electrical connection is made to the anode from anode bus bar 36 by means of a rigid conductive member 38 which can also serve to physically support anode 30 in its position within the trough l8. Conductive member 38 can of course be electrically insulated to reduce shock hazard.

Motion is imparted to the trough conveyor assembly by means of a cam 40 which is rotatably driven in a clockwise direction by suitable motive means, the cam cooperating with a cam follower 42, attached to or formed as part of hanger 22, in a manner to provide the novel plating operation according to the principles of the invention. The motive means can be electrical, hydraulic or pneumatic. A spring 44 attached between a support 46 and hanger 20 urges trough l8 and its associated suspension assembly into positive contact with the camming surface of cam 40. Alternatively, two cams or a twolobed cam may be used, in place of the single cam and spring illustrated, to provide the requisite forward and rearward trough motion. In some instances, return of the trough can be simply via gravity, and motion in either direction can be accelerative to achieve particular trough movement.

According to the invention, the trough conveyor assembly 12 is effective to transport items being plated through the plating solution in an effectively continuous manner by use of unique periodic movement which achieves uniform and complete plating. The unique periodic movement of the items being plated is accomplished by trough 18 which is caused to move longitudinally and upwardly in a first direction, thereby to longitudinally and upwardly transport items within the trough, and caused to move abruptly in an opposite direction, rapidly returning the trough to a rest position whereupon the items are momentarily suspended within the plating solution and are caused to fall onto the bottom surface of the trough in a position forward of their former position. The trough motion continues sequentially to increment the items along the trough, the items moving generally in a periodic fashion so that they are completely and continuously plated as they move through the plating solution by virtue of the novel system operation.

To achieve the novel trough motion, cam 40 is caused to rotate in a clockwise direction as illustrated in FIG. 1 by an arrow, causing trough 18 to move leftwardly and upwardly as seen in FIG. 1 as cam surface 48 cooperates with follower 42. When cam follower 42 reaches the abrupt discontinuity in camming surface 48, trough 18 is rapidly returned to the rest position, as illustrated, by the urging of spring 44 to provide the necessary abrupt return motion of the trough. The extent of trough movement is determined by the particular characteristics and location of cam 40 in conjunction with the dimensions of the hanger supports, while the frequency of trough motion is determined by the speed of rotation of cam 40. Particular degrees of trough motion and frequency can be determined to suit the requirements of specific plating operations.

The periodic trough motion lends itself to interruption of plating current during portions of the periodic cycle. Plating occurs essentially during the time when the items are in contact with the cathode disposed in the trough, that is during forward motion of the trough. To conserve power, or to modify the plating process, current can be switched off during return movement of the trough when the items are caused to fall through the bath to their reoriented positions forwardly of the trough. Such current interruption can be accomplished by a suitable switch activated by the trough conveyor, for example, by the cam 40 or one of the hangers 20 and 22.

in operation, items to be plated are contained within supply bin 14 and are delivered by means of a chute 50 to the supply end of trough 18. items can be fed from the supply bin to the plating bath, for example, by means of a well-known vibratory feed mechanism contained within bin 14. The items are deposited at the supply end of trough 18 in a random manner and these items are conveyed through the plating solution by the novel motion of trough 18, the items being periodically deposited by the cyclic action of trough 18 on successively leftward positions of the trough. The items experience sufficient random orientations during their progression through the solution such that all surfaces thereof are exposed to the plating solution. A continuous and uniform coating is thereby achieved by the cyclic conveyance provided by the invention. items at the leftmost end of trough 18 are transported by the same periodic movement onto conveyor 16 by which the plated items are removed from the plating bath. The items may then be transported by suitable conveyor means to subsequent baths for further plating operations or for cleaning or rinsing. Subsequent operations can be conducted by systems substantially similar to that described hereinabove, as can preplating operations such as degreasing.

Variations in the particular implementation of the invention can be made to suit process requirements. For example, the trough bottom can be configured to aid the orientation of articles as they fall thereon by virtue of the unique periodic trough motion. One such configured trough is illustrated in FIG. 3 and includes a plurality of inclined surfaces 60 arranged across the width of the trough and inclined longitudinally thereof, and appearing in the illustrated longitudinal section as a sawtooth pattern. As a trough with this configured bottom surface moves abruptly to its rest position (to the right in the figure) items being conveyed fall onto the inclined surfaces and tend to tumble downwardly of the inclines. Acceleration in the downward and rearward direction may also be used to increase the tumbling action. Thus, reorientation of items during their path through the bath is achieved to permit plating of all item surfaces. in some instances, the cathode LII electrode is preferably noncontinuous and such cathode can be implemented in the invention by providing discrete conductive areas along the length of the trough bottom.

Tandem or cascade operation can be provided by use of multiple troughs, mounted for motion as described hereinabove, and the trough can be partitioned along the length to provide, in effect, separate troughs useful for example in processing articles which tend to nest or become entangled.

Modifications in the trough suspension and conveyor assemblies can also be made. For example, in place of the parallel suspension described hereinabove, a plurality of resilient members attached to or formed as part of the trough can be employed to support the trough and permit requisite motion. The resilient supports can be of a plastic material suitable to allow the necessary bending required to achieve the unique periodic trough motion, and offer the advantage of eliminating bearings or pivots within the bath.

Other modifications and alternative implementations will now occur to those versed in the art without departing from the spirit and true scope of the invention. Accordingly, it is not intended to limit the invention by what has been particularly shown and described.

What is claimed is:

1. Apparatus for conveying articles through a liquid bath comprising:

a tank for containing a liquid;

an elongated trough movably supported within said tank and adapted to contain articles therein;

means for cyclically moving said trough with smooth motion in a first direction longitudinally and upwardly within said tank to transport said articles in said trough to a position longitudinally and upwardly from their initial position and abruptly in an opposite direction for rapidly returning said trough to its initial position thereby to cause momentary suspension of articles in said liquid and deposition of said articles through said liquid onto said trough in a position forward of their former position.

2. Apparatus according to claim 1 wherein said trough is supported within said tank by a plurality of hangers pivotally attached to said trough and operative to permit simultaneous longitudinal and upward movement thereof.

3. Apparatus according to claim 2 further including means for supplying articles to one end of said trough, and means for removing articles from said tank as said articles exit from the opposite end of said trough.

4. Apparatus according to claim 2 wherein said trough moving means includes a cam follower disposed on at least one of said hangers, and a rotatably driven cam cooperating with said cam follower, said cam having a first portion operative to urge said trough longitudinally and upwardly, and a second portion operative to permit abrupt return of said trough.

5. Plating apparatus comprising:

a tank for containing a plating solution;

an elongated trough formed of an electrically insulative material and having a cathode electrode disposed in the bottom thereof;

means supporting said trough within said tank in a position below the level of the plating solution contained therein and operative to permit pivotal parallel movement of said trough longitudinally and upwardly thereof;

motive means coupled to said supporting means and operative to cyclically move said trough with smooth motion in a first direction longitudinally and upwardly to transport articles contained in said trough to a position longitudinally and upwardly from their initial position, and abruptly in an opposite direction to the initial position thereof, thereby to cause momentary suspension of articles in said plating solution and deposition of said articles through said plating solution onto said trough in a position forward of the former position, and thus transport articles in said trough progressively along the length thereof; and

3,616,423 6 an anode electrode disposed in said tank in juxtaposition coextensive therewith.

with said trough. 7. Plating apparatus according to claim 5 wherein said 6. Plating apparatus according to claim 5 wherein said trough includesabottom surface configured to promote tumanode electrode includes an elongated conductive member blmg mono" ofsald article-5' disposed substantially parallel to said trough and substantially 5 

2. Apparatus according to claim 1 wherein said trough is supported within said tank by a plurality of hangers pivotally attached to said trough and operative to permit simultaneous longitudinal and upward movement thereof.
 3. Apparatus according to claim 2 further including means for supplying articles to one end of said trough, and means for removing articles from said tank as said articles exit from the opposite end of said trough.
 4. Apparatus according to claim 2 wherein said trough moving means includes a cam follower disposed on at least one of said hangers, and a rotatably driven cam cooperating with said cam follower, said cam having a first portion operative to urge said trough longitudinally and upwardly, and A second portion operative to permit abrupt return of said trough.
 5. Plating apparatus comprising: a tank for containing a plating solution; an elongated trough formed of an electrically insulative material and having a cathode electrode disposed in the bottom thereof; means supporting said trough within said tank in a position below the level of the plating solution contained therein and operative to permit pivotal parallel movement of said trough longitudinally and upwardly thereof; motive means coupled to said supporting means and operative to cyclically move said trough with smooth motion in a first direction longitudinally and upwardly to transport articles contained in said trough to a position longitudinally and upwardly from their initial position, and abruptly in an opposite direction to the initial position thereof, thereby to cause momentary suspension of articles in said plating solution and deposition of said articles through said plating solution onto said trough in a position forward of the former position, and thus transport articles in said trough progressively along the length thereof; and an anode electrode disposed in said tank in juxtaposition with said trough.
 6. Plating apparatus according to claim 5 wherein said anode electrode includes an elongated conductive member disposed substantially parallel to said trough and substantially coextensive therewith.
 7. Plating apparatus according to claim 5 wherein said trough includes a bottom surface configured to promote tumbling motion of said articles. 